Artificial Christmas Trees: How Real Are the Lead Exposure Risks?

Exposure to lead has long been recognized as a major public health issue in the United States and other industrialized nations. During the late 1980s and early 1990s, it was discovered that lead would cause permanent and irreversible neurological damage, especially in infants and young children, at far lower exposure levels than previously believed (McMichael et al., 1988; Sciarillo, Alexander, & Farrell, 1992). Although recent data show that baseline blood lead levels have been declining over the last two decades (Mattuck, Beck, Bowers, & Cohen, 2001), lead is still a significant threat to health, particularly in children.

A recent study involving multivariate analysis of 4,853 study subjects ranging in age from 6 to 16 years found reductions in cognitive performance associated with blood lead levels as low as 2.5 micrograms per deciliter ([micro]g/dL) (Lanphear, Dietrich, Auinger, & Cox, 2001). Thus, lead-containing products with even moderate potential to cause human exposure are becoming recognized as having public health significance. One particular study found that even children whose blood lead levels (BLLs) never exceeded the Centers for Disease Control and Prevention (CDC) level of concern (10 [micro]g/dL) could have decreases in IQ of 2.6 points per 10 [micro]g/dL increase in BLLs (Winter, 2001). In the most recent study of the neurological effects of low-level lead exposure, Canfield and co-authors (2003) found a 7.4-point IQ deficit (with a 95 percent confidence interval of 3.2-12.9 points, as measured by the Stanford-Binet Intelligence Scale and the Revised Wechsler Preschool and Primary Scale of Intelligence) as BLLs increased from 1 to 10 [micro]g/dL. This finding strongly suggests that neurological damage may be caused at even lower BLLs. This latest study, which tested 172 children ranging in age from six months to five years and measured nine confounding factors, further underscores the importance of identifying and addressing even relatively small lead exposure concerns.

Several meta-analyses have been done to further investigate the connection between BLLs and IQ deficits. Some researchers (Kaufman, 2001; Pocock, Smith, & Baghurst, 1994) suggest that although there is some evidence that supports the connection, other explanations need considering before definitive conclusions can be drawn on the subject. These researchers fear that recent studies have not adequately allowed for confounding factors and that other shortcomings in the studies may lead to improper conclusions. Other researchers (Needleman & Bellinger, 2001) argue that meta-analysis shows that lead does indeed have a negative impact on IQ, even when multiple variables have been controlled for in different statistical models.

In addition to intellectual effects, studies have connected lead exposure with behavioral and emotional problems, such as aggressive or anxious behavior, in children (Burns, Baghurst, Sawyer, McMichael, & Tong, 1999). Lead may also affect the growth of children, as was documented in a study that measured decreases in height, head circumference, and chest circumference with increasing lead levels (Kafourou et al., 1997).

Within the past 10 years, it has become recognized that polyvinyl chloride (PVC, or vinyl) plastic products often contain relatively large amounts of lead added as stabilizers. In 1995, it was discovered that imported vinyl mini-blinds contained so much lead that the surface dust produced as a result of direct sunlight and heat was resulting in cases of acute lead poisoning of young children who handled and played with them (Norman, 1996; B.C. Lee of U.S. Consumer Products Safety Commission, personal communication to M.F. Toro, July 24, 1996). Studies conducted in 1997 found that several commonly used children's products, such as PVC raincoats, book bags, and beach bags accumulated high levels of lead on surfaces after exposure to sunlight (DiGangi, 1997; Maas, Smith, Patch, & Thornton, 1997). …

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